Method and apparatus for user selectable display mode for intelligently enhancing battery life

ABSTRACT

A method and system for enhancing the life of a battery within a portable or otherwise battery operated electronic device. The method and system provide user selectable display modes, e.g., from color to monochrome, that can be changed in order to enhance the life of the device&#39;s battery. The monochrome display mode can be selected by the user when the battery level is detected below a predefined threshold. In one embodiment, the electronic device is a hand held computer system with a display device. When the battery level is detected as below a preselected level, a message is generated on the computer display screen. The message informs the user that the display mode of the screen can be changed to enhance the battery life. If selected, the display mode can change from color to monochrome thereby saving power because the monochrome display does not utilize a back-lighting element. In one embodiment, color sequential techniques are used to provide a flat panel color display. Within the display, a transreflective layer provides reflective light for monochrome applications. When the battery energy returns to normal levels, the color display mode can be re-entered automatically. It is appreciated that the display mode changes can also be performed automatically if the battery level falls below certain critical levels.

This is a continuation of application(s) Ser. No. 09/649,999 filed onAug. 28, 2000 now U.S. Pat. No. 6,603,469 which is hereby incorporatedby reference to this specification.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to the field of computer systems that arebattery operated and have display screens. More specifically, thepresent invention relates to portable electronic devices and systems.

2. Related Art

As the components required to build a computer system have reduced insize, new categories of computer systems have emerged. One of the newcategories of computer systems is the “palmtop” computer system. Apalmtop computer system is a computer that is small enough to be held inthe hand of a user and can therefore be “palm-sized.” Most palmtopcomputer systems are used to implement various Personal InformationManagement (PIM) applications such as an address book, a daily organizerand electronic notepads, to name a few. Palmtop computers with PIMsoftware have been know as Personal Digital Assistants (PDAs). Many PDAshave a small and flat display screen associated therewith.

In addition to PDAs, display screens have also been implemented withinother portable electronic devices, such as cell phones, electronicpagers, remote control devices and other wireless portable devices.

These portable electronic devices, such as PDAs, are often batterypowered. Some portable electronic devices utilize rechargeable batteriesand others use cells that need to be replaced after some limited periodof use. As portable electronic devices become more complexelectronically, their power consumption rates have also increased.Because they have limited battery energy, some PDAs and other electronicdevices, such as cells phone, electronic pagers, etc., have relativelyshort operational periods between which battery replacements orrecharging is required. With respect to rechargeable PDAs, cell phones,electronic pagers, etc., they typically have little more than a day ofstored battery energy before they need to be recharged. Therefore, itwould be desirable to provide an electronic device having a screen thatfunctioned in a way to enhance the device's battery life.

Certain PDAs manage their battery life in an intelligent manner. Forinstance, if the battery life of certain PDAs falls below apredetermined low level, the user is given a screen message indicatingthat a battery recharge or replacement is needed and should be doneright away. In this manner, the user can perform corrective actionbefore any information is lost. Therefore, it would be desirable toprovide an electronic device having a screen that enhanced and managedthe device's battery life in an intelligent manner.

Some color flat panel displays utilize a back lighting element, such asa cold cathode fluorescent (CCF) tube. These elements consume arelatively large amount of energy from a battery operated device. Itwould be desirable to provide an electronic device that offered a colordisplay but also managed the device's battery life in an intelligentmanner.

SUMMARY OF THE INVENTION

Accordingly, embodiments of the present invention provide an electronicdevice, e.g., a cell phone, PDA, electronic pager, etc., having a screenalso that functions in a way to enhance the device's battery life.Embodiments also provide an electronic device having a screen that alsoenhances and manages the device's battery life in an intelligent manner.Embodiments also provide an electronic device that offers a multi-modecolor display that also manages the device's battery life in anintelligent manner. The present invention provides these advantages andothers not specifically mentioned above but described in the sections tofollow.

A method and system are described herein for enhancing the life of abattery within a portable or otherwise battery operated electronicdevice. The method and system provide user selectable display modes,e.g., from color to monochrome, that can be changed in order to enhancethe life of the battery. In one embodiment, monochrome display modeconsumes less power than color display mode. For instance, themonochrome display mode can be selected by the user when the batterylevel is detected as falling below a predefined threshold. In oneembodiment, the electronic device is a hand held computer system with amulti-mode display device. When the battery level is automaticallydetected as falling below a preselected level, a message is generated onthe computer display screen. The message informs the user that thedisplay mode of the screen can be changed to enhance the battery life.If selected, the display mode can change from color to monochromethereby saving power because the monochrome display does not utilize aback-lighting element. In one embodiment, color sequential techniquesare used to provide a flat panel color/monochrome display. Within thedisplay, a transreflective layer provides reflective light formonochrome applications and bright light color applications. When thebattery energy returns to normal levels, the color display mode can bere-entered automatically. It is appreciated that the display modechanges can also be performed automatically if the battery level fallsbelow certain critical levels.

More specifically, an embodiment of the present invention includes aportable electronic device comprising: a battery; a processor coupled tobus; an input device coupled to the bus; a multi-mode display devicecoupled to the bus; a memory unit coupled to the bus wherein the memoryunit contains processor instructions that when executed implement amethod of enhancing battery life comprising the steps of: a) detecting abattery energy level of the portable electronic device below a firstpredetermined level, wherein the portable electronic device has amulti-mode display device; b) in response to step a), placing themulti-mode display device into a monochrome display mode to enhanceremaining battery life of the portable electronic device; c) detectingthe battery energy level of the portable electronic device above asecond predetermined level; and d) in response to step c), placing themulti-mode display device into a color display mode.

Embodiments include the above and wherein the multi-mode display devicecomprises: a) selectively energized multi-color lighting elements; b) acolor flat panel display layer utilizing color sequential scanningprocesses; and c) a transreflective layer positioned between themulti-color lighting elements and the color flat panel display layer.Embodiments include the above and wherein the step b) of the methodcomprises the steps of: b1) displaying a message on the multi-modedisplay device indicating a low battery state and also indicating a userselection between color and monochrome display modes; and b2) inresponse to a user selection of the monochrome display mode, placing themulti-mode display device into the monochrome display mode and whereinthe step b) further comprises the step of b3) automatically placing themulti-mode display device into the monochrome display mode, regardlessof the user selection, provided the battery level is below apredetermined critical low level.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is system illustration of a palmtop or “palm sized” computersystem connected to other computer systems and the Internet via a cradledevice.

FIG. 2A is a top side perspective view of a palmtop computer system thatcan be used in one embodiment of the present invention.

FIG. 2B is a bottom side perspective view of the palmtop computer systemof FIG. 2A.

FIG. 3 is an exploded view of the components of the palmtop computersystem of FIG. 2A.

FIG. 4 is a perspective view of the cradle device for connecting thepalmtop computer system to other systems via a communication interface.

FIG. 5 is a logical block diagram of the palmtop computer system inaccordance with an embodiment of the present invention.

FIG. 6 is a front view of a palm top computer system illustrating thedisplay screen, digitizer regions and an exemplary menu of a textdisplay application.

FIG. 7, FIG. 8 and FIG. 9 are flow diagrams illustrating one embodimentof the present invention for intelligently enhancing the battery life ofa battery powered computer system.

FIG. 10 illustrates an exemplary user message displayed in oneembodiment of the present invention for user selectably enteringmonochrome display mode to intelligently enhance the battery life of abattery powered computer system.

FIG. 11 illustrates another exemplary user message displayed in oneembodiment of the present invention indicating that monochrome displaymode has automatically been entered to intelligently enhance the batterylife of a battery powered computer system.

FIG. 12 is a cross sectional diagram of exemplary layers of a multi-modeflat panel display screen in accordance with one embodiment of thepresent invention.

DETAILED DESCRIPTION OF THE INVENTION

In the following detailed description of the present invention, a methodand system for providing user selectable display modes for a multi-modedisplay screen in order to intelligently enhance battery life for abattery powered electronic device, numerous specific details are setforth in order to provide a thorough understanding of the presentinvention. However, it will be recognized by one skilled in the art thatthe present invention may be practiced without these specific details orwith equivalents thereof. In other instances, well known methods,procedures, components, and circuits have not been described in detailas not to unnecessarily obscure aspects of the present invention.

Notation and Nomenclature

Some portions of the detailed descriptions which follow are presented interms of procedures, steps, logic blocks, processing, and other symbolicrepresentations of operations on data bits that can be performed oncomputer memory. These descriptions and representations are the meansused by those skilled in the data processing arts to most effectivelyconvey the substance of their work to others skilled in the art. Aprocedure, computer executed step, logic block, process, etc., is here,and generally, conceived to be a self-consistent sequence of steps orinstructions leading to a desired result. The steps are those requiringphysical manipulations of physical quantities. Usually, though notnecessarily, these quantities take the form of electrical or magneticsignals capable of being stored, transferred, combined, compared, andotherwise manipulated in a computer system. It has proven convenient attimes, principally for reasons of common usage, to refer to thesesignals as bits, values, elements, symbols, characters, terms, numbers,or the like.

It should be borne in mind, however, that all of these and similar termsare to be associated with the appropriate physical quantities and aremerely convenient labels applied to these quantities. Unlessspecifically stated otherwise as apparent from the followingdiscussions, it is appreciated that throughout the present invention,discussions utilizing terms such as “checking,” “accessing” “processing”or “computing” or “translating” or “calculating” or “determining” or“scrolling” or “displaying” or “recognizing” or the like, refer to theaction and processes of a computer system, or similar electroniccomputing device, that manipulates and transforms data represented asphysical (electronic) quantities within the computer system's registersand memories into other data similarly represented as physicalquantities within the computer system memories or registers or othersuch information storage, transmission or display devices.

Exemplary Palmtop Computer System Platform

FIG. 1 illustrates a system 50 that can be used in conjunction with theintelligent battery life enhancement features of the present invention.System 50 is exemplary and comprises a host computer system 56 which caneither be a desktop unit as shown, or, alternatively, can be a laptopsystem 58. Optionally, one or more host computer systems can be usedwithin system 50. Host computer systems 58 and 56 are shown connected toa communication bus 54, which in one embodiment can be a serialcommunication bus, but could be of any of a number of well knowndesigns, e.g., a parallel bus, Ethernet Local Area Network (LAN), etc.Optionally, bus 54 can provide communication with the Internet 52 usinga number of well known protocols.

Importantly, bus 54 is also coupled to a cradle 60 for receiving andinitiating communication with a palm top (“palm-sized”) portablecomputer system 100 of the present invention. Cradle 60 provides anelectrical and mechanical communication interface between bus 54 (andanything coupled to bus 54) and the computer system 100 for two waycommunications. Computer system 100 also contains a wireless infraredcommunication mechanism 64 for sending and receiving information fromother devices.

FIG. 2A is a perspective illustration of the top face 100 a of oneembodiment of the palmtop computer system that can be used in oneembodiment of the present invention. The top face 110 a contains adisplay screen 105 surrounded by a bezel or cover. A removable stylus 80is also shown. The display screen 105 contains a transparent touchscreen (digitizer) able to register contact between the screen and thetip of the stylus 80. The stylus 80 can be of any material to makecontact with the screen 105. As shown in FIG. 2A, the stylus 80 isinserted into a receiving slot or rail 350. Slot or rail 350 acts tohold the stylus when the computer system 100 a is not in use. Slot orrail 350 may contain switching devices for automatically powering downand automatically power up computer system 100 a based on the positionof the stylus 80. The top face 100 a also contains one or more dedicatedand/or programmable buttons 75 for selecting information and causing thecomputer system to implement functions. The on/off button 95 is alsoshown.

FIG. 2A also illustrates a handwriting recognition pad or “digitizer”containing two regions 106 a and 106 b. Region 106 a is for the drawingof alpha characters therein for automatic recognition (and generally notused for recognizing numeric characters) and region 106 b is for thedrawing of numeric characters therein for automatic recognition (andgenerally not used for recognizing numeric characters). The stylus 80 isused for stroking a character within one of the regions 106 a and 106 b.The stroke information is then fed to an internal processor forautomatic character recognition. Once characters are recognized, theyare typically displayed on the screen 105 for verification and/ormodification.

The digitizer 160 records both the (x, y) coordinate value of thecurrent location of the stylus and also simultaneously records thepressure that the stylus exerts on the face of the digitizer pad. Thecoordinate values (spatial information) and pressure data are thenoutput on separate channels for sampling by the processor 101 (FIG. 5).In one implementation, there are roughly 256 different discrete levelsof pressure that can be detected by the digitizer 106. Since thedigitizer's channels are sampled serially by the processor, the strokespatial data are sampled “pseudo” simultaneously with the associatedpressure data. The sampled data is then stored in a memory by theprocessor 101 (FIG. 5) for later analysis.

FIG. 2B illustrates the bottom side 100 b of one embodiment of thepalmtop computer system. An optional extendible antenna 85 is shown andalso a battery storage compartment door 90 is shown. A communicationinterface 108 is also shown. In one embodiment of the present invention,the serial communication interface 108 is a serial communication port,but could also alternatively be of any of a number of well knowncommunication standards and protocols, e.g., parallel, SCSI, Firewire(IEEE 1394), Ethernet, etc. In FIG. 2B is also shown the stylusreceiving slot or rail 350.

FIG. 3 is an exploded view of the palmtop computer system 100 inaccordance with one implementation of the present invention. System 100contains a front cover 210 having an outline of region 106 and holes 75a for receiving buttons 75 b. A flat panel display 105 (both liquidcrystal display and touch screen) fits into front cover 210. Any of anumber of display technologies can be used, e.g., LCD, FED, plasma,etc., for the flat panel display 105. In one embodiment, the display 105is a flat panel multi-mode display capable of both monochrome and colordisplay modes.

The touch screen can be a digitizer. A battery 215 provides electricalpower. Replaceable cells or rechargeable batteries can be used. Wellknown electronics coupled to the battery 215 can detect the energy levelof the battery 215. This information can be sampled by the computersystem 110 (FIG. 5) using well known techniques. The digitizer of FIG. 3can be implemented using well known devices, for instance, using theADS-7846 device by Burr-Brown that provides separate channels forspatial stroke information and pressure information. A contrastadjustment (potentiometer) 220 is also shown. On/off button 95 is shownalong with an infrared emitter and detector device 64. A flex circuit230 is shown along with a PC board 225 containing electronics and logic(e.g., memory, communication bus, processor, etc.) for implementingcomputer system functionality. The digitizer pad is also included in PCboard 225. A midframe 235 is shown along with stylus 80. Positionadjustable antenna 85 is shown. The midframe 235 contains the stylusreceiving slot or rail 350.

A radio receiver/transmitter device 240 is also shown between themidframe and the rear cover 245 of FIG. 3. The receiver/transmitterdevice 240 is coupled to the antenna 85 and also coupled to communicatewith the PC board 225. In one implementation, the Mobitex wirelesscommunication system is used to provide two way communication betweensystem 100 and other networked computers and/or the Internet via a proxyserver. In other embodiments, TCP protocol can be used.

FIG. 4 is a perspective illustration of one embodiment of the cradle 60for receiving the palmtop computer system 100. Cradle 60 contains amechanical and electrical interface 260 for interfacing with serialconnection 108 (FIG. 2B) of computer system 100 when system 100 is slidinto the cradle 60 in an upright position. Once inserted, button 270 canbe pressed to initiate two way communication between system 100 andother computer systems coupled to serial communication 265.

FIG. 5 illustrates circuitry of computer system 100, some of which canbe implemented on PC board 225. The computer system 100 can be used toperform the intelligent battery life enhancement processes of thepresent invention. Computer system 100 includes an address/data bus 99for communicating information, a central processor 101 coupled with thebus 99 for processing information and instructions, a volatile memory102 (e.g., random access memory RAM) coupled with the bus 99 for storinginformation and instructions for the central processor 101 and anon-volatile memory 103 (e.g., read only memory ROM) coupled with thebus 99 for storing static information and instructions for the processor101. Computer system 110 also includes an optional data storage device104 (e.g., memory stick) coupled with the bus 99 for storing informationand instructions. Device 104 can be removable. As described above,system 100 also contains a display device 105 coupled to the bus 99 fordisplaying information to the computer user. PC board 225 can containthe processor 101, the bus 99, the ROM 103 and the RAM 102.

Also included in computer system 110 of FIG. 5 is an alphanumeric inputdevice 106 which in one implementation is a handwriting recognition pad(“digitizer”) having regions 106 a and 106 b (FIG. 2A), for instance.Device 106 can communicate information (spatial data and pressure data)and command selections to the central processor 101. System 110 alsoincludes an optional cursor control or directing device 107 coupled tothe bus for communicating user input information and command selectionsto the central processor 101. In one implementation, device 107 is atouch screen device incorporated with screen 105. Device 107 is capableof registering a position on the screen 105 where the stylus makescontact and the pressure of the contact. The display device 105 utilizedwith the computer system 110 may be a liquid crystal device, cathode raytube (CRT), field emission device (FED, also called flat panel CRT) orother display device suitable for creating graphic images andalphanumeric characters recognizable to the user. In one embodiment, thedisplay 105 utilizes color sequential scanning but could also utilizecolor filters with subpixels.

Signal communication device 108, also coupled to bus 99, can be a serialport for communicating with the cradle 60. Device 108 can also includean infrared communication port.

FIG. 6 is a front view of the palmtop computer system 100 with a menubar 305 open displaying a pull down window having several selectionsthat can be made by the user. Buttons on screen 105 can be selected bythe user directly tapping on the screen location of the button withstylus 80. Also shown are two regions of digitizer 106 a and 106 b.Region 106 a is for receiving user stroke data (and pressure data) foralphabet characters, and typically not numeric characters, and region106 b is for receiving user stroke data (and pressure data) for numericdata, and typically not for alphabetic characters. Physical buttons 75are also shown. Although different regions are shown for alphabetic andnumeric characters, the device is also operable within a single regionthat recognizes both alphabetic and numeric characters. Also shown inFIG. 6 is the position of the stylus receiving slot or rail 350. It isappreciated that while the stylus receiving slot or rail 350 is depictedon the left of the computer 100, it can also be deployed on the right oralong the top edge or along the bottom edge.

It is appreciated that, in one embodiment, the digitizer region 106 aand 106 b are separate from the display screen 105 and therefore doesnot consume any display area.

Intelligent Battery Life Enhancement of the Present Invention

In accordance with embodiments of the present invention, the displaymode of the multi-mode display unit 105 can be altered in response todetected low battery life. By changing display modes in this fashion,the remaining battery life of the portable electronic device can beextended. Although the PDA device 100 has been illustrated as oneexample, it is appreciated that any of a number of portable or otherwisebattery powered electronic devices can be used within the spirit andscope of the present invention, e.g., electronic pagers, cell phones,computer systems, PDAs, etc., can utilize the intelligent batteryehancement processes of the present invention. In one embodiment, anydisplay mode changes are performed in response to a user selection wherethe user is cueued to make a selection after a low battery level isdetected by the electronic device. In another embodiment, all changesare performed automatically by the electronic device without requiring auser selection. In yet another mode, a user selection is requested, butif the battery level reaches a critical low level and the user has notyet made a low power selection, then the electronic device automaticallychanges to a low power display mode.

FIG. 7, FIG. 8 and FIG. 9 illustrate steps of a flow diagram thatrepresents one cyclic process 400 in accordance with an embodiment ofthe present invention. It is appreciated that process 400 can beimplemented, in one embodiment, as processor instructions stored incomputer readable memory units of the electronic device. At step 410,the device 100 checks if the multi-mode display 105 is already in themonochrome display mode. If the device 100 places the display 105 in themonochrome display mode, then a battery flag is also set concurrently.Alternatively, a display mode flag can be checked at step 410. If thedisplay is currently in monochrome display mode, then process “A” isentered. At step 420, the device 100 checks if the multi-mode display105 is in color display mode. In one embodiment, the same flag can beused to make this determination and, in fact, step 420 can also be adefault condition based on any negative determination made at step 410.If the display 105 is in color display mode, then process “B” isentered. At the completion of either process, A or B, step 430 isentered. After some predetermined duration, step 410 is then enteredagain.

FIG. 8 illustrates the steps of process A which represents the case ofthe multi-mode display being in monochrome display mode. At step 440,the device 100 checks the battery energy level of battery 215. As aresult of the check, a certain energy level value is given, e.g., thecurrent energy level. This value can be expressed as a voltage, apercentage, a time remaining, etc., or any other value appropriate torepresent the remaining energy level of battery 215 as indicated at thetime step 440 is performed. At step 445, a check is made if the currentenergy level is above a predetermined normal level. Any value can beassigned to the normal level. In one embodiment, it is 20 percent of thetotal battery energy capacity.

If the current energy level is above this predetermined normal level,then at step 450, the multi-mode display is automatically placed intothe color display mode. The display mode flag and any battery flags arealso set to indicate the color display mode. Step 450 is provided toreturn the device to color display mode when adequate battery energy isdetected. Since the display quality is increased, there is no need toask the user before automatically returning to the color display mode.After step 450, process A returns. At step 445 of FIG. 8, if it isdetermined that the current energy level of the battery 215 is below thenormal level, then process A returns directly and the multi-mode display105 remains in the monochrome display mode.

FIG. 9 illustrates the steps of process B which represents the case ofthe multi-mode display being in the color display mode. At step 460, thedevice 100 checks the battery energy level of battery 215. As a resultof the check, a certain energy level value is given, e.g., the currentenergy level. This value can be expressed as a voltage, a percentage, atime remaining, etc., or any other value appropriate to represent theremaining energy level of battery 215 as indicated at the time step 460is performed. At step 465, a check is made if the current energy levelis above the predetermined normal level. Any value can be assigned tothe normal level. If so, then at step 470, the display is left in thecolor display mode and process B returns.

At step 475, a check is made if the current energy level is below apredetermined critical level. Any value can be assigned to the criticallevel that is below the normal level. In one embodiment, the criticallevel is selected such hardly any battery energy is remaining in thedevice 100. In this case, at step 480, the multi-mode display 105 isautomatically placed into the monochrome display mode because themonochrome display mode consumes less energy than the color displaymode. Flags are also set indicating the setting of monochrome displaymode. At step 480, the device can also generate a user message as shownin FIG. 11. This message 570 informs the user that the battery energylevel is critically low and that monochrome mode is being entered inorder to extend remaining battery life. Optionally, at step 480, themessage 570 (FIG. 11) can also indicate the estimated time, X, remainingin the battery until forced power down. After step 480, process Breturns.

At step 485 of FIG. 9, a check is made if the current energy level isbelow a predetermined low level. Any value can be assigned to the lowlevel that is below the normal level and above the critical level. Thelow level and the normal level can also be the same level in oneembodiment. If the current level is not below the low level, thenprocess B returns. If the current level is below the low level (and notbelow the critical level), then step 490 is entered as long as the usermono flag is reset. If the user mono flag is set, then step 520 isentered. At step 490, a message (as shown in FIG. 10) is displayed tothe user informing them that the battery level is low and further givingthe user a choice between remaining in color display mode (displaybutton 560 b) or switching to monochrome mode (display button 560 a). Ifthey switch to monochrome mode, the message 550 can also give anestimate of the battery life remaining, N.

At step 495 of FIG. 9, a check is made if the user selected monochromemode, e.g., button 560 a. If so, then at step 510, the multi-modedisplay 105 is placed into monochrome display mode because themonochrome display mode consumes less energy than the color displaymode. Flags are also set indicating the setting of monochrome displaymode. Process B then returns. At step 495, if the user did not selectmonochrome mode, e.g., button 560 b or button 560 c, then at process 497the user mono flag is set and process B returns. The user mono flag doesnot reset until some long period of time so that the user is notcontinually bothered with the message at 490.

It is appreciated that process 400 does not replace any other batterylife warning processes that may also reside within device 100. Forinstance, if the device 100 is in monochrome display mode and thebattery energy level of device 100 falls below the critical level, acritically low battery warning may be given to the user.

FIG. 12 illustrates a multi-mode display that can be used in accordancewith one embodiment of the present invention. It is appreciated that anymulti-mode display device can be used by the present invention wherecolor display consumes more energy than the monochrome display. The flatpanel multi-mode display 105 a of FIG. 12 is shown as an example only.Display 105 a is a liquid crystal display that utilizes sequential colorscanning techniques. In accordance with well known sequential colorscanning, multi-color back lighting elements 650 are energized insynchronization with color data of the color being presented to thepixels of the LCD layer 630. In other words, the red elements areexcited in synchronization with the red data, the blue elements are thenexcited in synchronization with the blue data, and then the greenelements are excited in synchronization with the green data. This canoccur in any order.

A transreflector 640 is positioned between the back lighting elements650 and the LCD layer 650. In this embodiment, the transreflector 640 isalso a rear polarizer. In an alternative embodiment, a separate rearpolarizer can also be used (if the transreflector does not double as apolarizer) and the polarizer layer (not shown) would be placed adjacentto the transreflector layer 640. A front polarizer layer 620 is alsoused and is positioned between the LCD layer 630 and a touch panel layer610 (digitizer). It is appreciated that in color mode, the multi-colorback lighting elements 650 are energized. It is also appreciated that inmonochrome mode, the multi-color back lighting elements 650 are disabled(thereby saving power) and the transreflector 640 provides theappropriate light energy for viewing an image within the LCD layer 630.In color display mode, the transreflector 640 also provides theappropriate light energy for viewing an image within the LCD layer 630for environments having bright light, e.g., sunny viewing conditions.

In monochrome mode, the color data for a given pixel is averaged tocreate one gray scale. The pixel scanning speed is also reduced by ⅓ andthe multi-color back lighting elements 650 are disabled.

It is appreciated that the embodiments of the present invention can beapplied to any transreflective display technology that utilizes a backlight that can be selectively turned on and off. For instance, theembodiments of the present invention can be applied to a color displaythat is transreflective and has a back lighting element. The backlighting element can be turned off to save power. In this case, thedisplay is in color when the back lighting element is on and also incolor when the back lighting element is off. Also, the embodiments ofthe present invention can be applied to a monochrome display that istransreflective and has a back lighting element. The back lightingelement can be turned off to save power. In this case, the display is inmonochrome when the back lighting element is on and also in monochromewhen the back lighting element is off.

The preferred embodiment of the present invention, a method and systemfor providing user selectable display modes for a multi-mode displayscreen in order to intelligently enhance battery life for a batterypowered electronic device, is thus described. While the presentinvention has been described in particular embodiments, it should beappreciated that the present invention should not be construed aslimited by such embodiments, but rather construed according to the belowclaims.

1. In a portable electronic device, a method of enhancing battery lifecomprising the steps of: detecting a battery energy level of saidportable electronic device below a first predetermined level, whereinsaid portable electronic device comprises a multi-mode display device;in response to said detecting said battery energy level of said portableelectronic device below a first predetermined level, automaticallyplacing said multi-mode display device into a monochrome display mode toenhance remaining battery life of said portable electronic device;detecting said battery energy level of said portable electronic deviceabove said first predetermined level and below a second predeterminedlevel; and in response to said detecting said battery energy level ofsaid portable electronic device above said first predetermined level andbelow said second predetermined level, displaying a message on saidmulti-mode display device indicating a low battery level and alsoindicating a user selection between said monochrome display mode and acolor display mode.
 2. A method as described in claim 1 wherein saidportable electronic device is a palm sized computer system.
 3. A methodas described in claim 1 wherein said portable electronic device is awireless telephone.
 4. A method as described in claim 1 wherein saidmulti-mode display device comprises: selectively energized multi-colorlighting elements; a color flat panel display layer utilizing colorsequential scanning processes; and a transreflective layer positionedbetween said multi-color lighting elements and said color flat paneldisplay layer.
 5. A method as described in claim 4 wherein saidmulti-color lighting elements are disabled during said monochromedisplay mode.
 6. A method as described in claim 1 further comprising:detecting said battery level energy level of said portable electronicdevice above second predetermined level; and in response to saiddetecting said battery level energy level of said portable electronicdevice above second predetermined level, automatically placing saidmulti-mode display device into said color display mode.
 7. A method asdescribed in claim 1 further comprising: in response to a user selectionof said monochrome display mode, placing said multi-mode display deviceinto said monochrome display mode.
 8. A method as described in claim 1further comprising: in response to a user selection of said colordisplay mode, placing said multi-mode display device into said colordisplay mode.
 9. In a battery powered palm sized computer system, amethod of enhancing battery life comprising: detecting a battery energylevel of said computer system below a first predetermined level, whereinsaid computer system comprises a flat panel multi-mode display device;in response to said detecting a battery energy level of said computersystem below a first predetermined level, placing said flat panelmulti-mode display device into a monochrome display mode to enhanceremaining battery life of said computer system; detecting said batteryenergy level of said computer system above said first predeterminedlevel and below a second predetermined level; and d) in response to saiddetecting said battery energy level of said portable electronic deviceabove said first predetermined level and below said second predeterminedlevel, displaying a message on said flat panel multi-mode display deviceindicating a low battery level and also indicating a user selectionbetween said monochrome display mode and a color display mode.
 10. Amethod as described in claim 9 wherein said flat panel multi-modedisplay device comprises: selectively energized multi-color lightingelements; a color flat panel display layer utilizing color sequentialscanning processes; and a transreflective layer positioned between saidmulti-color lighting elements and said color flat panel display layer.11. A method as described in claim 10 wherein said multi-color lightingelements are disabled during said monochrome display mode.
 12. A methodas described in claim 9 further comprising: detecting said battery levelenergy level of said portable electronic device above secondpredetermined level; and in response to said detecting said batterylevel energy level of said portable electronic device above secondpredetermined level, automatically placing said multi-mode displaydevice into said color display mode.
 13. A method as described in claim9 further comprising: in response to a user selection of said monochromedisplay mode, placing said multi-mode display device into saidmonochrome display mode.
 14. A method as described in claim 9 furthercomprising: in response to a user selection of said color display mode,placing said multi-mode display device into said color display mode. 15.A portable electronic device comprising: a battery; a processor coupledto a bus; an input device coupled to said bus; a multi-mode displaydevice coupled to said bus; a memory unit coupled to said bus whereinsaid memory unit contains processor instructions that when executedimplement a method of enhancing battery life comprising: detecting abattery energy level of said portable electronic device below a firstpredetermined level; in response to said detecting said battery energylevel of said portable electronic device below a first predeterminedlevel, automatically placing said multi-mode display device into amonochrome display mode to enhance remaining battery life of saidportable electronic device; detecting said battery energy level of saidportable electronic device above said first predetermined level andbelow a second predetermined level; and in response to said detectingsaid battery energy level of said portable electronic device above saidfirst predetermined level and below said second predetermined level,displaying a message on said multi-mode display device indicating a lowbattery level and also indicating a user selection between saidmonochrome display mode and a color display mode.
 16. A portableelectronic device as described in claim 15 wherein said multi-modedisplay device comprises: selectively energized multi-color lightingelements; a color flat panel display layer utilizing color sequentialscanning processes; and a transreflective layer positioned between saidmulti-color lighting elements and said color flat panel display layer.17. A portable electronic device as described in claim 16 wherein saidmulti-color lighting elements are disabled during said monochromedisplay mode.
 18. A portable electronic device as described in claim 15wherein said method further comprises: detecting said battery levelenergy level of said portable electronic device above secondpredetermined level; and in response to said detecting said batterylevel energy level of said portable electronic device above secondpredetermined level, automatically placing said multi-mode displaydevice into said color display mode.
 19. A portable electronic device asdescribed in claim 15 wherein said method further comprises: in responseto a user selection of said monochrome display mode, placing saidmulti-mode display device into said monochrome display mode.
 20. Aportable electronic device as described in claim 15 wherein said methodfurther comprises: in response to a user selection of said color displaymode, placing said multi-mode display device into said color displaymode.
 21. In a portable electronic device, a method of enhancing batterylife comprising: detecting a battery energy level of said portableelectronic device below a first predetermined level, wherein saidportable electronic device comprises a transreflective display devicecomprising a back lighting element; in response to said detecting saidbattery energy level of said portable electronic device below a firstpredetermined level, automatically placing said transreflective displaydevice into a first display mode to enhance remaining battery life ofsaid portable electronic device wherein said first display mode disablessaid back lighting element; detecting said battery energy level of saidportable electronic device above said first predetermined level andbelow a second predetermined level; and in response to said detectingsaid battery energy level of said portable electronic device above saidfirst predetermined level and below said second predetermined level,displaying a message on said transreflective display device indicating alow battery level and also indicating a user selection between saidfirst display mode and a second display mode wherein said second displaymode enables said back lighting element.